In the conventional fracturing of wells, producing formations, new wells or low producing wells that have been taken out of production, a formation can be fractured to attempt to achieve higher production rates. Proppant and fracturing fluid are mixed and then pumped into a well that penetrates an oil or gas bearing formation. High pressure is applied to the well, the formation fractures and proppant carried by the fracturing fluid flows into the fractures. The proppant in the fractures holds the fractures open after pressure is relaxed and production is resumed. Various fluids have been disclosed for use as the fracturing fluid, including various mixtures of hydrocarbons, nitrogen and carbon dioxide.
Gelling agents are commonly used in hydraulic fracturing treatments in order to allow a fracturing fluid to carry sufficient amounts of proppant downhole. U.S. Pat. Nos. 3,775,069 and 3,846,310 disclose gelling agents that form water-sensitive gels for hydrocarbon fracturing fluids. Various chemicals known as breakers may be added to these gelled fracturing fluids in order to reduce the viscosity of the gel and return the fluid to a pre-gel consistency. Breakers may also be timed to delay the breaking of the gel until a desire amount of time has elapsed, usually long enough to allow a fracturing fluid to deliver sufficient proppant into the created fractures. By breaking the gel after successful delivery of proppant, the reduced viscosity fracturing fluid may then be recovered leaving the delivered proppant behind in the formation to prop open the created fractures.